Basic research on the determinants of magnetic relaxation in cells is proposed with the specific aims of testing current models for water proton relaxation by freely rotating protein molecules, measuring the contributions of local microdynamic anisotropy on water proton relaxation in both the transverse and longitudinal directions, measuring the consequences of magnetic relaxation coupling between the water proton spin systems in tissues and the macromolecular components, measuring the charges in water relaxation rates as a function of time after tissue samples are excised from test animals, comparing relaxation times in test animals obtained with an in vivo imaging research spectrometer with those obtained on a conventional relaxation spectrometer, measuring the relaxation rate changes of different normal and malignant samples obtained to cover a variety of pathologies, and monitoring the effect of pre-experiment physiological stress on the fundamental parameters T1 and T2 in animals as a function of organ. This research will be conducted on a variety of instrumentation including a dedicated 60 MHz pulsed NMR relaxation spectrometer, a field cycling magnetic relaxation dispersion spectrometer, and an in vivo and imaging spectrometer operating a 2 T with a usable bore of 22 cm.